Single crystal cerium doped yttrium aluminum garnet boules were grown by the Czochralski method. Cerium concentrations were held at 1.0 at. % (with respect to yttrium in an on stoichiometric charge) but melt stoichiometry ranged from 10.0 at. % yttria rich to 10.0 at. % alumina rich in 5.0% increments. Photo-luminescence, lifetime, and scintillation data demonstrate a measureable decrease in UV defect emission as the melt becomes alumina rich. This is strongly consistent with a suppression of equilibrium YAl3+ antisite defect concentrations in the boule as melt stoichiometry shifts towards alumina rich. This decrease does not alter thermoluminescence behavior, making the case that carrier traps and YAl3+ antisites are independent defects. Additionally, an aluminum in-diffusion post growth treatment indicates the observed change is from reduction of YAl3+ antisite defect concentrations alone, as opposed to alteration of antisite-vacancy complexes. The results culminate in a large increase in visible emission and produce an excellent resolution of 5.04 ± 0.07% (662 keV; 10 mm thick) with electronic noise subtraction on a photodiode.